Congress figures to step in before the bills are due, as it did last year. But if it doesn't, premiums for about 30% of beneficiaries could jump 22%, from $121.80 per month to $149 a month in January 2017, if the cost-of-living adjustment for Social Security is low, as expected. The COLA for next year is likely to be quite small: 0.2% to 0.8%. The actual rates for Part B (which covers the costs of doctor visits and outpatient care) will be announced in October and take effect January 1.

When Social Security COLAs are very low or nonexistent, as was the case this year, about 70% of folks are protected from paying more for Medicare than they receive in the form of a raise in their monthly benefit checks. That sticks other recipients with the bill, specifically:

those who enroll in Part B in 2017,

people who don’t have their premiums deducted from Social Security payments,

individuals with annual incomes above $85,000,

and people eligible for both Medicare and Medicaid.

For the last group, known as “dual eligibles,” Part B premiums are paid by the state where they live.